The first 4 letters in the words below have been removed. There is a common property held by the following six 6-letter words that make them somewhat unique when compared with other 6-letter words. What are the words and what is the unique property?

_ _ _ _le
_ _ _ _on
_ _ _ _cs
_ _ _ _ng
_ _ _ _ng
_ _ _ _ad

Also, can you find any other 6-letter words with the same property as those above?